Deskewing device for corrugated cardboard manufacturing system

ABSTRACT

A deskewing device for a moving web of material in a corrugated cardboard manufacturing system incorporates a plurality of successive processing units that are equipped with processing tools, which are movable crosswise to the direction of conveyance of the web of material. A skew measuring device is provided to determine the skew of the web of material. It has a first position sensor, at least one second position sensor, which determine the transverse position of the web of material at predetermined longitudinal positions. A control unit is used to calculate from the data of the position sensors the skew of the web of material and the transverse position of the processing tools is corrected accordingly.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention is concerned with a deskewing device for a moving web of material, especially a sheet of paper, in a paper processing machine, such as, e.g., a corrugating machine.

[0003] 2. Background Art

[0004] In corrugated cardboard manufacturing systems, inaccuracies in the guide means for the various webs of material can cause the webs of material to move askew relative to a desired direction of conveyance. A deskewing device is known from U.S. Pat. No. 5 906 305, wherein a pendulum-style roller is used to correct the skew of the moving web of material. Existing systems in particular are not easily retrofitted with compensating devices of this type.

SUMMARY OF THE INVENTION

[0005] The present invention has as its aim to create a device whereby the skew of a moving web of material in a paper processing machine can be detected and compensated for in the simplest manner possible.

[0006] This aim is attained in a deskewing device for a moving web of material, especially a sheet of paper in a paper processing machine, such as, e.g., a corrugating machine, with a web of material to be transported along a desired direction of conveyance and transported along an actual direction of conveyance; with at least one processing unit for processing the web of material wherein the at least one processing unit incorporates at least one processing tool, which is movable crosswise to the desired direction of conveyance by means of an actuating drive, which can be brought into engagement with the web of material, and which is disposed at an actual transverse position yIST_(w) and at a longitudinal tool position x_(w); with a skew measuring device for determining the actual direction of conveyance of the web of material, wherein the skew measuring device incorporates at least one first position sensor disposed at a first longitudinal position x_(s1) to determine a first transverse position y_(s1) of the web of material, and at least one second position sensor disposed at a second longitudinal position X_(s2) to determine a second transverse position y_(s2) of the web of material; and with a control unit, which is connected in a data-transferring manner to the at least one first position sensor, the at least one second position sensor, and the at least one actuating drive, and which is designed in such a way that its actual direction of conveyance is determined from the first transverse position y_(s1) and second transverse position y_(s2) of the web of material, that the desired transverse position ySOLL_(w) of the at least one processing tool is determined from that actual direction of conveyance, and the at least one actuating drive for shifting the corresponding processing tool into the desired transverse position ySOLL_(w) is actuated. The gist of the invention is that the transverse position of a moving web of material is determined at two different successive longitudinal positions and the skew of any other randomly selected longitudinal position can be determined from it. At the processing units that are disposed along the web of material, the processing tools are automatically corrected regarding their position according to the determined lateral deviation. It is thus not necessary to shift the processing units crosswise in their entirety. Additionally, it is possible to determine the required compensation for the skew as accurately as possible.

[0007] Additional characteristics and details of the invention will be come apparent from the description of three embodiments with the aid of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 shows a schematic top view of an inventive device according to a first embodiment,

[0009]FIG. 2 shows a side view of the device according to FIG. 1,

[0010]FIG. 3 shows a top view of the device according to FIG. 1

[0011]FIG. 4 shows a front view according to the viewing arrow IV in FIG. 2,

[0012]FIG. 5 shows a schematic illustration of the mode of operation of the device according to FIG. 1,

[0013]FIG. 6 shows a schematic top view of an inventive device according to a second embodiment,

[0014]FIG. 7 shows a top view of the device according to FIG. 6,

[0015]FIG. 8 shows a schematic top view of a device according to a third embodiment, and

[0016]FIG. 9 shows a top view of the device according to FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A first embodiment of the invention will be described below with reference to FIGS. 1 through 5. A corrugated cardboard manufacturing system incorporates a longitudinal cutting and corrugating machine 1 through which a corrugated cardboard web 2 is guided along a desired direction of conveyance 3. The machine 1 incorporates, along the direction of conveyance 3, an edge-cutting station 4, a first corrugating station 5, a second corrugating station 6, as well as a first longitudinal cutting station 7, as well as a second longitudinal cutting station 8.

[0018] The edge cutting station 4 incorporates, in the region of the lateral edges 9 of the corrugated cardboard web 2, two rotating cutters 11 that are pivotable around a vertical pivoting axis 10 and disposed below the corrugated cardboard web 2 and can be brought into engagement with the corrugated cardboard web 2. The cutters 11 are shiftable crosswise to the direction of conveyance 3 by means of an assigned actuating drive 12. The cutters 11, as well as the actuating drives 12, are supported across from side walls 13 of a machine support 14. The detailed design of the edge cutting station 4, which permits the cutting of endless edge strips during format changes, is known from U.S. Ser. No. 08/503 425.

[0019] The corrugating stations 5 and 6 have pairs of tool beds 15, 16, as well as 17, 18, that are supported between opposing side walls 13. The tool beds 15 and 16, as well as 17 and 18, are disposed above one another in pairs, namely approximately mirror-symmetrically to the corrugated cardboard web 2. The tool beds 15 through 18 each are pivotable around a horizontal pivoting axis. Disposed on the sides of the tool beds 15 through 18 that face the corrugated cardboard web 2, are guide rails 19, on which tool holders 20 through 23, which are again assigned to one another in pairs, are disposed horizontally and shiftable crosswise to the direction of conveyance 3. Provided on the upper tool holders 20 and 21 are corrugating tools 24 and 25 that work together with respective counterpart corrugating tools 26 and 27 that are disposed underneath them on the tool holders 22 and 23. The tools 24 through 27 are drivable by means of belt drives 28. The corrugating stations 5, 6, additionally incorporate a rotatably mounted threaded spindle 29 that extends perpendicular to the direction of conveyance 3 and is drivable by means of a spindle motor 30 connected to the threaded spindle 29. The individual corrugating tools 24 through 27, of which a plurality are disposed on each given tool holder 20 through 23, can be coupled to the corresponding threaded spindle 29 to effect a shifting of the corresponding corrugating tool 24 through 27. In this manner one threaded spindle 29 may be used to shift a plurality of tools 24 through 27 disposed along a threaded spindle 29, either individually or all of them together. Reference is made to U.S. Ser. No. 09/924 098 of the applicant's for the detailed design of a 1-spindle positioning unit. Regarding the detailed design of the corrugating stations 5 and 6, as well as the longitudinal cutting stations 7 and 8, reference is made to U.S. Ser. No. 09/203 575.

[0020] The longitudinal cutting stations 7 and 8 incorporate, below the corrugated cardboard web 2, in a manner that matches the design of the corrugating stations 5 and 6, pivotable tool beds 31 and 32, on which, disposed on tool holders 33, 34 and shiftable crosswise to the direction of conveyance 3, cutters 35 are provided that are drivable by means of a corresponding belt drive 28. The cutters 35 can be brought into engagement with the corrugated cardboard web 2 and work together with rotatably driven brush rollers 36, 37 that are disposed above the corrugated cardboard web when the cutters 35 are immersed in the corrugated cardboard web. Regarding the transverse travel of the cutters 35, reference is made to the description of the corrugating stations 5 and 6.

[0021] A means for measuring a skew of the corrugated cardboard web 2 incorporates two cross supports 38 and 39 that are connected to the side walls 13 and extend crosswise to the direction of conveyance 3 above the corrugated cardboard web 2. The cross support 3 8 is disposed at the end of the edge cutting station 4 that is located in the direction of conveyance 3. The cross support 39 is disposed at the beginning of the longitudinal cutting station 7. Disposed on the cross supports 38 and 39, approximately above the edges 9 of the web of material 2, are cameras 40 that have a recording range 41. The cameras 40 are commercially available cameras, especially digital cameras, that are suitable for subsequent image processing to measure the position of the edges 9. The cameras 40 are connected via signal lines 42 to a control unit 43 which, in turn, is connected via signal lines 44 to the spindle motors 30.

[0022] The following is a description of the deskewing of the corrugated cardboard web 5, with reference especially to FIG. 5. It should be noted that FIG. 5 is not true to scale and represents a significant simplification of the machine 1 in order to better explain its operation. The desired movement 45 of a corrugated cardboard web 2 through the machine 1 extends parallel to the desired direction of conveyance 3. Malfunctions in the corrugated cardboard manufacturing system may cause the corrugated cardboard web 2 to travel along an actual direction of conveyance 46 that is askew and not parallel to the desired direction of conveyance 3. FIG. 5 shows only the cameras 40 that are disposed above the right edge 9 in the direction of conveyance 3, and two cameras 40 are also disposed in the region of the left edge 9. The cameras 40 are disposed at two known longitudinal positions x_(s1) and x_(s2.) With the cameras 40 the transverse position of the edge 9 is determined, which is referred to as y_(s1) and y_(s2.) From this data, i.e., two known points that are given in a Cartesian coordinate system, the position of the edge 9 can be calculated at any other randomly selected longitudinal position. Any inaccuracies can be eliminated in such a way that the determined position data of the left edge 9 and right edge 9 are compared to one another. The measured data from the cameras 40 are routed via the lines 42 to the control unit 43, which calculates the travel of the corrugated cardboard web 2. From the measured data, the desired transverse position ySOLL_(w,) that corresponds to the skewed travel of the corrugated cardboard web 2 is calculated for the given tools 24 through 27 and 35. A corresponding control signal is subsequently routed via the lines 44 to the corresponding motor 30, which, via the threaded spindle 29, shifts the corresponding tool from the actual transverse position yIST_(w) into the desired transverse position ySOLL_(w.) As a rule, all tools 24 through 27 and 35 that are assigned to one threaded spindle 29 are moved all at once, based on the required deskewing. Since the required corrections, as a rule, are relatively small shifting movements, the tools 24 through 27 and 35 may also be moved crosswise while they are in engagement with the corrugated cardboard web 2. The placement of the stations 4 through 8 has the particular advantage that the edge cutting station 4 precedes the corrugating stations 5 and 6 and longitudinal cutting stations 7 and 8. This enables the cameras 40 to follow the course of a cut edge 9, which has a much clearer and straighter contour than an uncut edge 9. Utilizing the measuring data from two cameras that are disposed at one level of the corrugated cardboard web 2 is particularly important when a change in the format occurs and the outer contour of the edge 9, therefore, does not extend straight but curved. By utilizing the data of the position of the left and right edge 9 of the corrugated cardboard web 2 it is possible to precisely determine the skew of the corrugated cardboard web 2 and calculate in advance the deviation of a desired transverse position from an actual transverse position at any random longitudinal position of the corrugated cardboard web 2. With the skew measuring device it is additionally also possible to compensate for a lateral displacement of the corrugated cardboard web 2. While, in this case, the actual direction of conveyance 46 of the corrugated cardboard web 2 does run parallel to the desired direction of conveyance 3, the corrugated cardboard web 2 does not move centrically through the machine 1 but is offset crosswise. The correction of such a lateral web displacement can also be performed with the inventive device without changes to the same. The transverse position of the corrugated cardboard web 2 can also take place by means of a marking that is provided on the corrugated cardboard web 2, e.g., an imprinted line.

[0023] A second embodiment of the invention will be described below, with reference to FIG. 6 and 7. Identical parts will be given the same reference numerals as in the first embodiment, and reference is hereby made to that description. Parts that are different in their design but have the same function are given the same reference numeral with a prime mark. The main difference compared to the first embodiment lies in the fact that the edge cutting station 4 is located downstream from the stations 5 through 8. Two cameras 40′ are accordingly disposed before the first station 5, as well as between the stations 6 and 7 which, as in the first embodiment, record the position of the edge 9 of the corrugated cardboard web 2. Placing station 4 after the stations 5 through 8 results in the cameras 40 each recording one uncut edge 9. The placement according to the second embodiment is used particularly when, for operational reasons, the edge cutting must take place after the corrugating stations 5 and 6 and longitudinal cutting stations 7 and 8.

[0024] A third embodiment of the invention will be described below with reference to FIG. 8 and 9. Identical parts will be given the same reference numerals as in the first embodiment, and reference is hereby made to that description. Parts that are different in their design but have identical functions are given the same reference numerals with two prime marks. As in the first embodiment, the stations 4 through 8 are disposed successively along the direction of conveyance 3. The main difference compared to the first embodiment is that no provision is made for a first pair of cameras 40 in the direction of conveyance 3. The function of the first two position sensors is assumed by the actuating drives 12 of the edge cutting station 4. The actuating drives 12 are connected via lines 42 to the control unit 43. The control unit 43 at all times has information regarding at which transverse positions the cutters 11 are disposed. The transverse positions of the cutters 11 thus correspond to the transverse position data y_(s1) of the front camera pair 40 in the first embodiment. From that transverse position data, as well as the transverse position data from the subordinate camera pair 40″, the skew of the corrugated cardboard web 2 is determined by the control unit 43. This embodiment has the advantage that only two cameras 40″ are needed and not four cameras 40, as in the first embodiment. 

What is claimed is
 1. A deskewing device for a moving web of material (2), especially a sheet of paper in a paper processing machine, such as, e.g., a corrugating machine, comprising a) a web of material (2) to be transported along a desired direction of conveyance (3) and transported along an actual direction of conveyance (46); b) at least one processing unit (4, 5, 6, 7, 8) for processing the web of material (2) wherein the at least one processing unit (4, 5, 6, 7, 8) incorporates at least one processing tool (11, 24, 25, 26, 27, 35), i) which is movable crosswise to the desired direction of conveyance (3) by means of an actuating drive (30), ii) which can be brought into engagement with the web of material (2), and iii) which is disposed at an actual transverse position yIST_(w) and at a longitudinal tool position x_(w); c) a skew measuring device for determining the actual direction of conveyance (46) of the web of material (2), wherein the skew measuring device incorporates i) at least one first position sensor (40, 40′; 12) disposed at a first longitudinal the web of material (2), and ii) at least one second position sensor (40; 40′; 40″) disposed at a second longitudinal position x_(s2) to determine a second transverse position y_(s2) of the web of material (2), and d) a control unit (43), i) which is connected in a data-transferring manner to the at least one first position sensor (40; 40′; 12), the at least one second position sensor (40; 40′; 40″), and the at least one actuating drive (30), and ii) which is designed in such a way that its actual direction of conveyance (46) is determined from the first transverse position y_(s1) and second transverse position y_(s2) of the web of material (2), that the desired transverse position ySOLL_(w) of the at least one processing tool (11, 24, 25, 26, 27, 35) is determined from that actual direction of conveyance (46), and the at least one actuating drive (12, 30) for shifting the corresponding processing tool (11, 24, 25, 26, 27, 35) into the desired transverse position ySOLL_(w) is actuated.
 2. A device according to claim 1, wherein the web of material (2) has two lateral edges (9).
 3. A device according to claim 2, wherein the position sensors (40; 40′; 12, 40″) are designed such that they determine the transverse position of at least one edge (9) of the web of material (2).
 4. A device according to claim 3, wherein the position sensors (40; 40′; 12, 40″) measure the transverse position of both edges (9) of the web of material (2).
 5. A device according to claim 1, wherein the actuating drive (30) incorporates a drivable threaded spindle (29).
 6. A device according to claim 5, wherein the at least one processing tool (11, 24, 25, 26, 27, 35), to shift it crosswise, can be coupled to the threaded spindle (29).
 7. A device according to claim 2, wherein a processing unit (4) is designed as a unit for cutting the edges (9) of the web of material (2).
 8. A device according to claim 7, wherein the unit for cutting the edges (9) incorporates cutters (11) that are positionable by a cutter actuating drive (12) into a predetermined crosswise cutter position y_(M).
 9. A device according to claim 8, wherein the cutter actuating drive (12) forms the at least one first position sensor (12).
 10. A device according to claim 1, wherein the at least one first position sensor (40; 40′; 12) and the at least one second position sensor (40; 40′; 40″) are disposed at different longitudinal positions x_(s1) and x_(s2) of the web of material (2). 